So no-one in the 13-18 age bracket owns anything other than iOS devices?

I'm fifteen and nearly all of the time use PGP-encrypted IM/email to communicate.

calling bs on that right now

I believe kunai but agree that use of encryption in messaging is very atypical, regardless of age.

I'd say that's mostly due to outside use. If your friends don't care about encryption, you would never use it. Since I have an extremely small social circle, I can afford to use encryption because I can actually convince people to use it.

iMessage is free. It works on Macs, iPhones, iPods and iPads.

I don't know what the usage stats are like, but those factors are probably worth a lot to teenagers who either have to pay their own phone bills, or have to convince their parents to do it.

In my experience we send "email" type communication almost exclusively by Facebook messaging.

I have never in my life written or received an email from someone in my age bracket intended to communicate. When my classmates and I use email, it is to share attachments or to communicate with adults.

iMessage is just slightly nicer SMS. Very common in Apple-heavy social groups and not that useful in others.

I have a 13-year-old daughter. She and all of her friends use email. Also iMessage ad WhatsApp. And they pretty much all have Facebook profiles as well.